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An angiogram is a type of X-ray used to examine blood vessels.
Blood vessels don't show up clearly on ordinary X-rays, so a special dye is injected into the area being examined. The dye highlights the blood vessels as it moves through them. The medical name for this is a catheter angiogram.
Less commonly, angiograms can also be carried out using magnetic resonance imaging(MRI) and computerised tomography (CT) techniques.
These pages mainly focus on catheter angiograms.
Why angiograms are used
An angiogram can help diagnose conditions that affect blood vessels and the flow of blood through them. These include:
- coronary heart disease – the blood flow through the artery that supplies the heart muscle is disrupted because it has become narrowed
- aneurysm – a section of a blood vessel wall bulges outwards due to a weakness in the wall
- atherosclerosis – blood vessels become clogged up with fatty substances, such as cholesterol; an angiogram can be used to assess the level of atherosclerosis in specific blood vessels
The image on an angiogram can also be used to help plan procedures such as angioplasty and stenting or surgery.
Read more about what an angiogram is used for.
The following short film is of Dr Peter Henriksen, Consultant Cardiologist for NHS Scotland, explaining what you need to know before having coronary angioplasty and stenting.
An angiogram is carried out in hospital. It takes between 30 minutes and 2 hours, depending on the complexity of the procedure. You will usually be allowed to go home on the same day, although in some cases you may need to stay in hospital overnight.
In most cases, angiograms are planned procedures that are performed under local anaesthetic. However, general anaesthetic may be used if young children need to have the procedure.
The doctor will feed a catheter (a very thin, flexible tube) into one of your arteries, usually through an incision (cut) in your groin or wrist. They will then guide the catheter into the area that needs to be examined, while a radiographer moves the X-ray machine into position for the images. The dye (medically known as a contrast dye or contrast medium) is injected through the catheter and into the blood vessel. A series of X-rays is then taken.
Read more about what happens during an angiogram.
An angiogram is a generally safe and painless procedure. The risks of serious complications are low.
Sometimes, an angiogram can cause bruising where the catheter is inserted. Also, some people may occasionally have an allergic reaction to the contrast dye. This is usually easily treated with medication.
Read more about the complications of an angiogram.
What angiography is used for
If you have circulation problems, your GP may recommend that you have an angiogram to find out what's causing the problem. The results of an angiogram can also help to determine suitable treatment options.
Dense areas of your body such as your bones and, to a lesser extent, certain organs, such as your lungs, absorb X-rays, so they show up as clear white areas on X-ray images. However, conventional X-rays don't produce clear images of blood vessels and blood flow.
During an angiogram, a special type of dye (medically known as a contrast dye or contrast medium) is injected into the area where the blood vessels are to be examined. Like your bones and other dense areas of the body, the contrast dye absorbs X-rays.
As the contrast dye moves through your blood vessels, a series of X-rays can be taken to examine how it moves. By tracking its movement, it's possible to identify any problems with the blood vessels, such as blockages or sections that are unusually narrow.
Head and neck
A similar procedure that's used to study the blood vessels in your head and neck is called a cerebral angiogram.
A cerebral angiography may be used if it's thought that the blood vessels supplying blood to your brain (the carotid arteries) have become narrowed, disrupting the flow of blood. This can be dangerous because it could trigger a stroke or a transient ischemic attack(mini-stroke).
If you've had a stroke, a cerebral angiogram can be used to assess the extent of the damage to the blood vessels. In some cases, it may be able to pinpoint the underlying cause of a stroke.
A cerebral angiogram can also help to identify an aneurysm (a bulge in the blood vessel wall in your brain) or a brain tumour, which is an abnormal growth of tissue in the brain. Studying the flow of blood to the tumour can help to determine whether it's growing, which can be useful when planning treatment.
Coronary angiography is used to study the blood vessels that supply the heart muscle. It may be used if you have any of the following conditions:
- heart attack – a serious medical emergency where the supply of blood to the heart is suddenly blocked, usually by a blood clot
- angina – chest pain that occurs when the blood supply to the heart is restricted
- coronary heart disease – your heart muscle's blood supply is blocked or interrupted by a build-up of fatty substances in the coronary arteries (the blood vessels that supply the heart)
A coronary angiogram may also be used if you have a heart condition. It helps to determine the most appropriate type of treatment for you. This might be:
- a coronary angioplasty and stenting – a procedure to widen blocked or narrowed coronary arteries
- coronary artery bypass graft – a surgical procedure to divert blood around narrow or clogged arteries in order to improve the blood flow to the heart muscle
- aortic valve replacement – surgery to treat problems that affect the aortic valve, which is the valve that controls the flow of blood out of the left ventricle of the heart to the body’s main artery, the aorta
A pulmonary angiogram can be used to examine the blood vessels in the lungs. It's usually done when a person has a blood clot in one of the blood vessels in their lungs. This is known as a pulmonary embolism.
Performing a traditional catheter angiogram carries a high risk of complications. Therefore, another type of angiography, known as a computerised tomography pulmonary angiography (CTPA), is usually the preferred option.
A CTPA involves injecting contrast dye into the blood vessels of your lungs before taking a CT scan. If you have a pulmonary embolism in one of your lungs, it will show up on the CT scan as a blockage in your blood supply.
Arms and legs
An extremity angiogram can be used to examine the blood vessels in your arms and legs. This procedure is often used if it's thought that the blood supply to your leg muscles has become restricted. This is known as peripheral arterial disease and it causes a range of symptoms, the most common of which is painful cramping when walking.
An extremity angiogram can also be used to check for narrowing and hardening of the arteries (atherosclerosis, see below) in the arms and legs.
Renal angiograms can be used to examine the blood vessels in your kidneys. It may be recommended if you have symptoms, which suggest that the blood supply to your kidneys has been blocked in some way.
These symptoms include:
- high blood pressure (hypertension) that doesn't respond to treatment with medication
- swelling in certain areas of your body, such as your feet, due to a build-up of fluid (oedema)
- symptoms of kidney disease, such as itchy skin and blood in your urine
Atherosclerosis is a condition in which one or more of the arteries becomes narrowed and hardened due to a build-up of fatty materials, such as cholesterol. These types of material are collectively known as plaques.
Atherosclerosis is potentially dangerous because it can lead to organ failure and tissue death (gangrene). Plaques may also rupture causing events such as a heart attack or stroke.
During its early stage, atherosclerosis doesn't usually cause any noticeable symptoms, so the most effective method for early diagnosis is to identify people who are in high-risk groups and test them for the condition. High-risk groups for atherosclerosis include people who:
- are over 40 years old
- are overweight or obese
- smoke or have a previous history of heavy smoking
- have a high-fat diet
- have uncontrolled high blood pressure
- are diabetic
- have high cholesterol
- have a family history of cardiovascular disease
- are from south Asian ethnic decent
An angiogram is usually only carried out if initial tests, such as blood cholesterol tests and blood pressure tests, suggest that atherosclerosis is likely and symptoms have developed.
An angiography can also be used to:
- locate the site of internal bleeding
- detect blood clots
- investigate injuries to organs
- plan surgery that involves the blood vessels
Why angiography is necessary
If you have problems with your circulation, your GP may recommend an angiogram to find out what's causing the problem. The results will help decide what the treatment options are.
As blood vessels supply blood to every part of your body, any part can be affected by circulation problems. The major internal organs (your heart, brain and kidneys) and the extremities (your arms and legs) are affected if the blood supply to them is changed by blockages or arterial disease (disease of the arteries).
Problems caused by serious arterial disease include:
- heart attacks
- gangrene (tissue death)
- organ failure
Therefore, problems with your circulation should be investigated as soon as possible. The condition of your arteries can be assessed, and appropriate treatment options suggested.
How angiography is performed
Depending on the complexity of the investigation, an angiography takes between 30 minutes and 2 hours. You will usually be allowed to go home on the same day, although in some cases you may need to stay in hospital overnight.
An angiography is usually a planned procedure. However, it may occasionally be done on an emergency basis – for example, in the case of a heart attack.
In cases where an angiogram is planned, you're likely to have an initial appointment to discuss a number of issues. As part of these discussions, you may be asked:
- about your medical history
- whether you have any allergies
- whether you're currently taking any medication
You may also have a number of standard tests shortly before having an angiogram. These may include:
- blood pressure
- blood tests to check how well organs, such as your kidneys or liver, are working
- heart rate (pulse, ECG)
Before having an angiogram, some people may be offered a sedative to help them relax. You will be asked not to eat for several hours before having the procedure. Your care team will be able to give you a precise recommendation.
Most angiography procedures are carried out using local anaesthetic to numb the area of skin where the catheter (see below) is going to be inserted.
However, general anaesthetic (where you're asleep) is sometimes used when young children need to have the procedure. This is because it may be upsetting for them or they may find it too difficult to stay still during the procedure.
An angiogram is usually carried out by a senior doctor who specialises in cardiology, a radiographer (to operate the X-ray equipment), a cardiac technician (to monitor your heart during the procedure) and a nurse (to assist with the procedure itself).
An intravenous (IV) line will be inserted into a vein in your arm. It can be used to deliver sedatives or any other medication as required. Electrodes (small, metallic discs) are also placed on your chest to monitor your heart during the procedure. A blood pressure monitor will be attached to your arm.
A catheter (a thin, flexible tube) is then inserted into one of your arteries, usually either in the groin or wrist.
The doctor will use X-rays or, in some cases, a CT or MRI scanner, to help guide the catheter to the area being examined. Contrast dye will then be injected through the catheter, and a series of X-rays will be taken.
The procedure isn't painful, but you may feel a slight sensation of warmth or a mild burning sensation as the contrast dye moves through your blood vessels. It can take between 30 minutes and 2 hours to complete the procedure, depending on the complexity of your condition and the condition of your arteries.
In some cases, other procedures can be carried out during an angiogram, such as inserting a balloon, or a small tube called a stent, through the catheter to open up a narrowed artery. This is known as an angioplasty.
Once the procedure has been completed, the catheter will be removed and the incision will be closed using manual pressure, a plug or a clamp.
Following an angiogram, you will usually be taken to a recovery ward. You will be asked to lie still for a few hours to prevent bleeding at the site of the incision. After having an angiogram, most people are able to leave hospital on the same day. However, you may occasionally need to stay in overnight for observation. You'll be able to eat and drink as soon as you feel ready to. It may take a few hours before you're well enough to get up and walk around.
Depending on what the doctor finds during your angiogram, they may be able to discuss your results with you shortly after the procedure. A full report of the results of your investigation and any procedure carried out will be sent to your doctor.
Complications of angiography
Minor complications that can occur following an angiography procedure include:
- excessive bleeding at the site of the incision
- infection at the incision site, which may need to be treated with antibiotics
- a mild to moderate allergic reaction to the contrast dye; this can usually be controlled using anti-allergy medication
More serious complications can include:
- blood clots
- kidney damage
- blood vessel damage
- a serious, life-threatening allergic reaction (anaphylaxis) to the contrast dye
These serious complications are very rare. For example, only an estimated 1 in 1,000 people will have a stroke as a result of having an angiogram; approximately 1 in 50,000 to 150,000 people will experience anaphylaxis.
In almost every case, the benefit of having an angiogram far outweighs any potential risk.
16 December 2022
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